Prior infidelity emerged as an important risk factor for infidelity in next relationships, according to a recent study. Researchers addressed risk for serial infidelity by following adult participants (n=484) longitudinally through 2 mixed-gender romantic relationships. Participants reported their own extra-dyadic sexual involvement (ESI) (ie, having sexual relations with someone other than their partner) as well as both known and suspected ESI on the part of their partners in each romantic relationship. They found:

• Those who reported engaging in ESI in the first relationship were 3 times more likely to report engaging in ESI in their next relationship compared to those who did not report engaging in ESI in the first relationship.
• Similarly, compared to those who reported that their first-relationship partners did not engage in ESI, those who knew that their partners in the first relationships had engaged in ESI were twice as likely to report the same behavior from their next relationship partners.
• Those who suspected their first-relationship partners of ESI were 4 times more likely to report suspicion of partner ESI again in their next relationships.